Functional Genomic Study of Aging and Aging Intervention

衰老的功能基因组研究和衰老干预

• 批准号: 7327063
• 负责人: Sige Zou
• 金额: --
• 依托单位: NATIONAL INSTITUTE ON AGING
• 依托单位国家: 美国
• 资助国家: 美国
• 起止时间: 至
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/7327063
• 关键词: Functional; Genomic; Study; Aging; Intervention

The aim of this project is to identify aging-regulated genes at the molecular and tissue levels, to investigate molecular mechanisms of lifespan extension by longevity genes, and to identify efficient prolongevity interventions. To achieve our goals, we are utilizing three invertebrate systems, the Mexican fruit fly (mexfly), A. ludens, and the fly, D. melanogaster, and the nematode, C. elegans. Lifespan is influenced by a number of genetic and environmental factors. One of the most robust environmental manipulations of lifespan is dietary restriction (DR). DR has been shown to extend lifespan in many species, ranging from invertebrates to mammals, indicating that DR might retard aging if applied in humans. However, it would be challenging to impose long-term DR in humans. An alternative strategy would be to apply pharmaceutical or nutraceutical compounds to induce responses that would mimic DR. A few compounds have been shown to have this effect in model organisms. However, the number is still small and little is known about mechanisms by which these compounds extend lifespan. Genetic analyses of model organisms have uncovered mutations in a number of genes that can affect lifespan. Changes in gene expression in aging have been observed in a number of organisms, including worms, flies, rodents, primates and human beings. However, little is known about how different tissues age, and how longevity genes and prolongevity interventions influence aging. To address tissue-specific aging, we have systematically investigated tissue-specific factors that affect lifespan and aging processes. We have measured the expression profile of aging for seven tissues from fly, including brain, muscle and tissues in the digestive and reproductive systems, which represent different physiological functions. Hundreds of genes have been identified to show significant changes at the transcript level in aging in each tissue. Very few of these tissue-specific changes were shared among all the tissues, suggesting that different tissues age in unique ways. However, some of the aging-related changes are shared among two or more tissues, suggesting that common molecular features do exist among different tissues in aging. As an example, we have found genes involved a major metabolic pathway, TCA cycle, are down-regulated in brain, gut, muscle and testis but not fat tissue, accessory gland and malpighian tubule in aging. To study the mechanisms of lifespan extension by the longevity genes at the tissue and molecular levels, we have chosen to study the methuselah mutant fly, which has an extended lifespan. We have measured molecular changes of this mutant across age for the seven tissues described above. We have compared these changes to those in the wild type fly strain at the molecular and tissue levels. Several hundreds of genes have been identified to have tissue-specific changes between wild type and methuselah flies. This assessment will elucidate molecular and cellular mechanisms on how the methuselah gene regulates lifespan at the tissue level. Similar approaches will be applied to study mechanisms by which prolongevity interventions extend lifespan at the tissue levels in the future. Dietary supplements are widely used with the belief that they can forestall disease and increase longevity. Few systematic attempts have been made to confirm prolongevity claims made or to investigate potentially effective interventions. We are currently developing a high-throughput system by using mexfly. The main reason to use mexflies is that we have easy access to millions of mexflies available daily in the Moscafrut mass-rearing facility at Tapachula, Chiapas, Mexico. This minimizes our efforts to obtain a large number of animals for mortality analysis required for the high-throughput lifespan screen. There are several other advantages as well. The size of mexflies is relatively large relative to D. melanogaster so that it is easy to sort out by sex and to measure food intake, the latter of which is critical for assessing dosage effects of compounds. Moreover, unlike D. melanogaster, mexflies and medflies can feed on a dry food source but lay their eggs on a different medium such as organdy mesh, which facilitates investigation of effects of compounds on reproduction independent of diet. Finally, the expected lifespan of mexflies on a regular diet is approximately 2 months, which is short enough for conducting a lifespan screen and but long enough for demographic studies of aging. As an example, we have assessed the effects of supplementation of two related antioxidants, alpha-tocopherol and gamma-tocopherol, on lifespan of mexflies. We have found that these two antioxidants have marginal effects on lifespan extension, which is consistent with what we have observed in D. melanogaster. Utilization of the high-throughput system will provide reliable and statistically convincing results on the effects of aging interventions. Systematic evaluation of prolongevity interventions will not only allow identification of effective anti-aging compounds but also uncover mechanisms of lifespan extension by dietary supplementation. This approach should prove valuable to advance the objective of experimental gerontology to investigate and develop aging interventions in mammals. Our understanding of molecular mechanisms of DR comes primarily from studies of genetically amenable systems including yeast, worms, and flies, where DR has been imposed by either diluting the food source or by using genetic mutations that reduce feeding efficiency. However, a major drawback of these approaches is that there remains substantial uncertainty in determining the exact caloric intake of individuals under these DR paradigms, unlike this ability in studies of higher organisms. This led us to discover and develop an alternative dietary paradigm that can extend lifespan in C. elegans. We have found that a dietary deprivation (DD) regimen, in which the food source is completely removed from adults, can prolong adult lifespan by 45%. Since this regimen involves complete removal of the food source, the problem of controlling food intake, which has hampered interpretation of past studies, is alleviated. Using this unambiguous method, we have started investigating the genetic pathways necessary for lifespan extension by diet. Genome-wide transcript profiles of DD response are measured and compared to that of DR to reveal similarities between DD and DR paradigm. To identify which genetic pathways are required for the DD response, a genetic screen is being conducted for DD-associated genes identified from genomic studies as well as for genes known to extend lifespan. This analysis should reveal mechanisms governing longevity under different environmental especially dietary conditions. Considering the similarities between DD and DR, some of the DD mechanisms should be evolutionarily conserved, which will advance knowledge about effects of diet on aging and longevity in mammals. In summary, we have applied three different invertebrate species to address issues related to dietary regulation of lifespan by taking advantage of unique features of each system. With D. melanogaster, we are studying mechanisms by which prolongevity interventions and longevity genes extend lifespan at molecular and tissue levels. We are using mexflies to identify effective prolongevity interventions, which should provide guidance for further investigation of aging interventions in mammals. By utilizing a unique and robust dietary regimen in C. elegans, we are dissecting molecular mechanisms of dietary regulation of lifespan. Identification of the conserved features in aging and efficient prolongevity interventions are clearly critical for us

该项目的目的是在分子和组织水平上鉴定衰老调节的基因，以研究长寿基因延长寿命扩展的分子机制，并确定有效的延长性干预措施。为了实现我们的目标，我们正在利用三个无脊椎动物系统，即墨西哥果蝇（Mexfly），A。Ludens和Fly，D。Melanogaster和Melanogaster和线虫，C。Elegrans。寿命受许多遗传和环境因素的影响。饮食限制（DR）是最强大的环境操纵之一。 DR已被证明可以延长许多物种的寿命，范围从无脊椎动物到哺乳动物，表明如果在人类中应用，DR可能会延迟衰老。但是，将长期DR施加在人类中是一项挑战。另一种策略是将药物或营养化合物应用于模仿DR的反应。已经证明了一些化合物在模型生物中具有这种作用。但是，这个数字仍然很小，对这些化合物延长寿命的机制知之甚少。模型生物的遗传分析在许多可能影响寿命的基因中发现了突变。在许多生物中，包括蠕虫，蝇，啮齿动物，灵长类动物和人类在内的许多生物中都观察到了衰老中基因表达的变化。然而，关于不同的组织年龄以及寿命基因和延长性干预措施如何影响衰老的方式知之甚少。为了解决组织特异性衰老，我们已经系统地研究了影响寿命和衰老过程的组织特异性因素。我们已经测量了来自苍蝇的七个组织的衰老的表达谱，包括消化和生殖系统中代表不同生理功能的脑，肌肉和组织。已经确定了数百个基因在每个组织的衰老中显示出重大变化。这些组织特异性的变化中很少有在所有组织中共享，这表明不同的组织以独特的方式衰老。但是，某些与衰老相关的变化在两个或多个组织之间共享，这表明在衰老的不同组织中确实存在共同的分子特征。例如，我们发现涉及主要代谢途径，TCA循环的基因在大脑，肠道，肌肉和睾丸中被下调，而不是脂肪组织，牙科腺体和马尔皮亚小管中的衰老中。为了研究组织和分子水平的寿命基因的寿命扩展的机制，我们选择研究寿命延长的甲壳虫突变体蝇。我们已经在上述七个组织中测量了该突变体的分子变化。我们将这些变化与分子和组织水平的野生型蝇菌株中的变化进行了比较。已经确定了数百种基因在野生型和甲壳虫蝇之间具有组织特异性的变化。该评估将阐明有关甲壳虫基因如何调节组织水平寿命的分子和细胞机制。类似的方法将应用于研究机制，通过这些方法，ProLongevity干预措施将来会在组织水平上延长寿命。饮食补充剂被广泛使用，认为它们可以防止疾病并增加寿命。很少有系统地尝试确认提出的ProLongevity主张或调查潜在的有效干预措施。我们目前正在使用MexFly开发高通量系统。使用Mexflies的主要原因是，我们可以轻松地在墨西哥Chiapas的Tapachula的Moscafrut群众群体中每天提供数百万个Mexflies。这最大程度地减少了我们为获得大量动物进行高通量寿命屏幕所需的死亡率分析的努力。还有其他几个优势。相对于黑色素杆菌，Mexflies的大小相对较大，因此很容易通过性排列并测量食物摄入量，而后者对于评估化合物的剂量效应至关重要。此外，与D. melanogaster不同，Mexflies和Medflies可以以干性食物来源为食，但将鸡蛋放在不同的培养基上，例如Organdy网状，这有助于研究化合物对饮食独立于饮食的繁殖作用的研究。最后，常规饮食中预期的Mexflies的寿命约为2个月，足够短，足以进行寿命屏幕，但足够长的时间用于人口统计学研究。例如，我们评估了补充两种相关抗氧化剂，α-生育酚和γ-生育酚对Mexflies寿命的影响。我们发现，这两种抗氧化剂对寿命延伸具有边际影响，这与我们在D. melanogaster中观察到的相一致。高通量系统的利用将为衰老干预措施的影响提供可靠且具有统计学上令人信服的结果。对ProLongevity干预措施的系统评估不仅可以鉴定有效的抗衰老化合物，而且还可以通过补充饮食来识别寿命延长的机制。这种方法应该证明是有价值的，以促进实验老年病的目标，以调查和发展哺乳动物的衰老干预措施。我们对DR的分子机制的理解主要来自对包括酵母，蠕虫和果蝇在内的遗传熟悉系统的研究，在这些系统中，通过稀释食物来源或使用降低喂养效率的基因突变来施加DR。但是，这些方法的一个主要缺点是，在这些DR范式下确定个体的确切热量摄入量仍然存在很大的不确定性，这与对较高生物体的研究的能力不同。这使我们发现并开发了一种替代性饮食范式，可以在秀丽隐杆线虫中延长寿命。我们发现，饮食剥夺（DD）方案，其中完全从成年人中删除食物来源，可以将成人寿命延长45％。由于该方案涉及完全去除食物来源，因此控制食物摄入的问题阻碍了过去研究的解释。使用这种明确的方法，我们已经开始研究饮食延长寿命所需的遗传途径。测量了DD响应的全基因组转录谱，并将其与DR的DD进行比较，以揭示DD和DR范式之间的相似性。为了确定DD反应所需的遗传途径，正在为从基因组研究中确定的DD相关基因以及已知延长寿命的基因进行遗传筛选。该分析应揭示在不同环境尤其是饮食条件下延长寿命的机制。考虑到DD和DR之间的相似性，某些DD机制应在进化上保守，这将提高人们对饮食对哺乳动物衰老和寿命的影响的了解。总而言之，我们已经应用了三种不同的无脊椎动物，以利用每个系统的独特特征来解决与寿命饮食调节有关的问题。借助D. melanogaster，我们正在研究延长的干预措施和寿命基因在分子和组织水平上延长寿命的机制。我们正在使用Mexflies来识别有效的Prolongevity干预措施，这应该为进一步研究哺乳动物的衰老干预措施提供指导。通过利用秀丽隐杆线虫中的独特且坚固的饮食方案，我们正在解剖生命周期饮食调节的分子机制。鉴定衰老和有效的ProLongevity干预措施中保守特征对我们显然至关重要